What are the differences in AIX 5.1,

> Hi,
>
> Upgraded from AIX 4.3.2 to AIX 5.1, while running database backups the
> perfomance is degraded.
> What are the factors that have changed from 4.3 to 5.1 which might affect
> the performance?
>
> Thanks,
> Kiran.

Hello
Have you set the vmtune parameter. We set our vmtune -P 20 -p 10 to keep the system from pageing the same info as the database. The database will place data in memory and so will the system and this can result n excessive paging. Check to see if you are paging over 10-20 percent. If so the vmtune may help you.

Make sure that you have increased your max aioservers and setup vmtune
parameters properly depending on your real memory amount. Usually, it
takes 30 aioservers to startup an Oracle 9i Database. And then you must
multiply that value by two if it is small database with low query demands.
Set your max aioservers to a high number an restart the server. Then after
all of the databases are up an running run the command "pstat -a | grep aio
| wc -l " to look at how many aioservers have been issued. If the number
is the same as your max setting then you will need too increase the max
aioservers again to an higher number less than 1000.

I encountered a similar problem after upgrading to 5.1.
Performance was very low only during backups (300Kb/s !), but disk bench was
correct.
I use Time Navigator software from Atempo, I just increase the buffer
transfer size from 32K to 128K (specific Atempo parameter xdr_buf_size) and
everything is OK now.
If it can give you an idea ...

I encountered a similar problem after upgrading to 5.1.
Performance was very low only during backups (300Kb/s !), but disk bench
was
correct.
I use Time Navigator software from Atempo, I just increase the buffer
transfer size from 32K to 128K (specific Atempo parameter xdr_buf_size) and
everything is OK now.
If it can give you an idea ...

This buffer is used and initiated by the backup agent daemon.
I tried to get more information on www.atempo.com, but site is very poor.
I don't know what backup system Kiran is using, but perhaps is there a
similar option to pass to the daemon.

The formula you have is a very gerneral rule of thumb. Because today's
processors are more powerful this formula does not completely fit an
accurate tunning process. It is use a starting point. If you have an
medium to large database were heavy transcation are executed then max
aioservers issued will be higher for that individual database. Since most
servers are running several databases it if little different trying to find
the correct level of max aioservers. If all possible never set the max
aioservers higher than 950 an rule of thumb that I always have used in the
past. If you reached this setting then the database will have to compete
with other databases running on that server to grab freed or unused
aioservers to complete thier process.

In short, if after you have restart you server and all of the databases are
running check to see how many aio servers were needed to launch all of your
databases. That will be your min aio server setting if less than 500.